Barrier film and method for preparing the same

ABSTRACT

Provided are a barrier film and a method for preparing the same. Particularly, the barrier film is applied to an organic or inorganic phosphor, a display, or a photovoltaic device to effective block chemical materials such as water or oxygen, protect an electronic device therein, and maintain excellent optical characteristics.

BACKGROUND

1. Field of the Invention

The present invention relates to a barrier film and a method forpreparing the same.

2. Discussion of Related Art

When electric devices and metal interconnections included in organic orinorganic phosphors, displays, photovoltaic devices, etc. are in contactwith external chemical materials such as oxygen or water, they aremodified or oxidized, and thus cannot be properly functioning.Accordingly, it is necessary to protect the electric devices from thechemical materials. To this end, a technique of protecting internalelectric devices vulnerable to chemical materials using a glass plate asa substrate or a cover plate has been proposed. The glass plate hassatisfactory characteristics including light transmittance, acoefficient of thermal expansion, and chemical resistance. However,since glass is heavy, hard, and easily breakable, it should be carefullyhandled.

Accordingly, there is an active attempt to replace the glass plate usedas a substrate for an electric device with a plastic film or sheet,which is a representative material having a lighter weight, an excellentimpact resistance, and higher flexibility, compared with the glassplate. However, it is necessary to complement deficient physicalproperties of a plastic film commercially produced these days, comparedwith the glass plate. Particularly, it is most urgently necessary toimprove water resistance and gas barrier properties among the physicalproperties of the plastic film, compared with the characteristics of theglass plate, and a barrier film showing excellence both in gas barrierproperties and light transmittance is required.

PRIOR ART DOCUMENT

1. Japanese Laid-Open Patent Application No. 2007-090803

SUMMARY OF THE INVENTION

The present invention is directed to providing a barrier film applied toan organic or inorganic phosphor device, a display device, or aphotovoltaic device to effectively block environmental chemicalmaterials such as water or oxygen, protect an electronic device therein,and maintain excellent optical characteristics, and a method ofmanufacturing the same.

In one aspect, the present invention provides a barrier film. In oneexample, the barrier film of the present invention may be applied to anorganic or inorganic phosphor device, a display device, or aphotovoltaic device. The exemplary barrier film 10, as shown in FIG. 1,may sequentially include a base layer 14, a first dielectric layer 13,an inorganic layer 12, and a second dielectric layer 11, and satisfyGeneral Formula 1. Here, the inorganic layer may have a refractive indexof 1.65 or more. In addition, a thickness of the first dielectric layermay be less than 100 nm, and a thickness of the second dielectric layermay be equal to or larger than that of the first dielectric layer. Thatis, the thickness of the second dielectric layer may be equal to orlarger than that of the first dielectric layer. Meanwhile, the inorganiclayer may have a refractive index of at least 1.65 or more, for example,1.7 or more, 1.75 or more, 1.8 or more, 1.85 or more, 1.9 or more, 1.95or more, 1.96 or more, 1.97 or more, 1.98 or more, 1.99 or more, or 2.0or more. The upper limit of the refractive index of the inorganic layermay be, but is not particularly limited to, for example, 3.0 or less,2.5 or less, 2.4 or less, 2.3 or less, or 2.2 or less. The presentinvention may provide a barrier film having gas barrier properties andexcellent optical characteristics by controlling the thicknesses andrefractive indices of the first dielectric layer and the seconddielectric layer in addition to the inorganic layer having a relativelyhigh refractive index.

n ₂ ≦n ₁ <n _(i)  [General Formula 1]

In General Formula 1, n₁ represents the refractive index of the firstdielectric layer, n₂ represents the refractive index of the seconddielectric layer, and n_(i) represents the refractive index of theinorganic layer.

Optical characteristics of the film having a structure in which severallayers are laminated are changed by the refractive indices andthicknesses of the components layer. Particularly, since the reflectionand refraction of light occur at an interface between two layers havingdifferent refractive indices, the laminating materials, which give riseto the difference in refractive index among the laminated layers, andthe lamination sequence have profound effects on the opticalcharacteristics of the multilayer film. The first dielectric layer, theinorganic layer, and the second dielectric layer may be formed ofmaterials known to those of ordinary skill in the art without limitationas long as the materials satisfy the relationship of the refractiveindices, and as the relationship of the refractive indices and thethickness relationship are satisfied, the barrier film having excellentoptical characteristics may be manufactured.

The term “refractive index” used herein may be, unless particularlydefined, a refractive index in the range of a wavelength from 300 to1000 nm. In one example, the “refractive index” used herein may refer toa refractive index in a wavelength of 550 or 633 nm.

In addition, the barrier film of the present invention having excellentoptical characteristics may be manufactured by satisfying the thicknessrelationship according to General Formula 4.

0.01≦d ₁ /d ₂≦1  [General Formula 4]

In General Formula 4, d₁ is the thickness of the first dielectric layer,and d₂ is the thickness of the second dielectric layer.

As described above, a ratio of the thickness of the first dielectriclayer d₁ to the thickness of the second dielectric layer d₂ may be 0.01to 1, or 0.01 or more and less than 1, for example, 0.02 to 1.0, 0.05 to1.0, 0.1 to 1.0, 0.1 to 0.9, 0.1 to 0.8, or 0.1 to 0.7. As describedabove, as the ratio of the thickness between the first dielectric layerand the second dielectric layer is limited to a specific range, a filmhaving excellent gas barrier properties and light transmittance may bemanufactured.

As described above, the thickness of the first dielectric layer d₁ maybe less than 100 nm, for example, 5 to 98 nm. In addition, the thicknessof the first dielectric layer may be 10 to 95 nm, 10 to 90 nm, 10 to 85nm, 10 to 80 nm, or 10 to 75 nm. That is, the relationship of thethickness between the first dielectric layer and the second dielectriclayer, which satisfies General Formula 4 of the present invention, maybe established when, for example, the thickness of the first dielectriclayer is less than 100 nm. In addition, in one example, the thickness ofthe second dielectric layer d₂ may be 10 nm to 1 μm, 10 to 900 nm, 20 to800 nm, 30 to 700 nm, 35 to 600 nm, 40 to 500 nm, or 45 to 400 nm. Asthe thickness relationship is satisfied, the first dielectric layer andthe second dielectric layer of the present invention may realizeexcellent gas barrier properties and light transmittance with thefollowing zinc oxide-based inorganic layer having a higher refractiveindex than a silicon oxide-based inorganic layer.

In addition, in an exemplary embodiment of the present invention, therefractive index of the first dielectric layer n₁ and the refractiveindex of the second dielectric layer n₂ may satisfy General Formula 2.

0.5≦(n ₂−1)/(n ₁−1)≦1  [General Formula 2]

As shown in General Formula 2, the ratio (n₂−1)/(n_(i)−1) of therefractive index of the second dielectric layer n₂ to the refractiveindex of the first dielectric layer n₁ may be 0.5 to 1, preferably, 0.55to 1, 0.6 to 1, 0.65 to 1, or 0.7 to 1.

In addition, in an exemplary embodiment of the present invention, therefractive index of the first dielectric layer n₁ and the refractiveindex of the inorganic layer n_(i) may satisfy General Formula 3.

0.3≦(n ₁−1)/(n _(i)−1)≦0.95  [General Formula 3]

As shown in General Formula 3, the ratio (n₁−1)/(n_(i)−1) of therefractive index of the first dielectric layer n₁ to the refractiveindex of the inorganic layer n_(i) may be 0.3 to 0.95, preferably 0.35to 0.85, 0.4 to 0.8, 0.4 to 0.75, 0.4 to 0.7, or 0.45 to 0.7.

According to the present invention, a film having excellent lighttransmittance may be manufactured by limiting the ratio of therefractive indices between the first dielectric layer and the seconddielectric layer and/or the ratio of the refractive indices between theinorganic layer and the second dielectric layer in a specific range.

In an exemplary embodiment of the present invention, the refractiveindex of the base layer may be, but is not particularly limited to, 1.45to 1.75, 1.45 to 1.7, or 1.5 to 1.65. As long as satisfying GeneralFormula 1, the refractive index of the first dielectric layer n₁ or therefractive index of the second dielectric layer n₂ may be, but is notparticularly limited to, 1.35 to 1.9, 1.4 to 1.9, 1.45 to 1.9, or 1.45to 1.8.

In addition, when the refractive index of the base layer is n_(s), therefractive index of the base layer may be lower than the refractiveindex of the inorganic layer n₁. In one example, the refractive index ofthe base layer n_(s) and the refractive index of the inorganic layern_(i) may satisfy General Formula 5.

n _(s) <n _(i)  [General Formula 5]

In the present invention, the refractive index of the base layer n_(s)and the refractive index of the first dielectric layer n₁ may alsosatisfy General Formula 6.

0.5≦n _(s) /n ₁≦1.5  [General Formula 6]

That is, the material for the base layer of the present invention is notparticularly limited, but may satisfy General Formula 5 or 6. Forexample, the ratio (n_(s)/n₁) of the refractive index of the base layern_(s) to the refractive index of the first dielectric layer n₁ may be0.5 to 1.5, and specifically, 0.6 to 1.4 or 0.7 to 1.3.

The relationship between the thickness of the first dielectric layer andthat of the second dielectric layer of the barrier film may be suitablycontrolled according to material characteristics and relationship of therefractive indices of the layers, and characteristics of the inorganiclayer of the barrier film, and satisfy General Formula 4. For example,as the thickness relationship is satisfied, excellent gas barrierproperties and light transmittance may be realized with a zincoxide-based inorganic layer that will be described below.

The barrier film may also have excellent light transmittance in thevisible region. In one example, the present invention may exhibit lighttransmittance of 88% or more in the wavelength range of 380 to 780 nm.In the present invention, the barrier film sequentially including thebase layer, the first dielectric layer, the inorganic layer, and thesecond dielectric layer may maintain excellent transparency. Forexample, the barrier film formed by satisfying the specific relationshipof the refractive indices among the layers or the relationship of thethickness ratio may have light transmittance of 88% or more, 89% ormore, or 90% or more in the range of a wavelength from 380 to 780 nm.

In addition, the barrier film may exhibit a lower yellowness index andexcellent light transmittance. In one example, when the specificrelationship of the refractive indices among the layers or therelationship of the thickness ratio is satisfied, the barrier filmhaving a lower yellowness index may be provided. For example, theyellowness index according to ASTM E313 may be −2.0 to 2.0, −1.8 to 1.8,−1.5 to 1.9, or −1.3 to 1.8.

In addition, the barrier film may have a b* value of the CIE coordinatesystem in a range of −1.0 to 1.5 or −0.5 to 1.3. The CIE coordinatesystem is a color level defined in the Commission Internationale del'Eclairage (CIE), and is also referred to as the CIE colorimetricsystem or the CIE color space. The coordinate system is a uniform colorspace coordinate, and a coordinate system today standardized in theworld because it has very small difference from the color recognition ofhuman eyes. The CIE coordinate system is defined by L* denotingbrightness and a* and b* denoting chromaticity, and the a* and b*represent directions of the color. Specifically, when the a* value is apositive number, it represents the red direction, when the a* value is anegative number, it represents the green direction, when the b* value isa positive number, it represents the yellow direction, and when the b*value is a negative number, it represents the blue direction. The b*value of a barrier film may be determined by a known method.

In an exemplary embodiment of the present invention, the firstdielectric layer, the inorganic layer, and the second dielectric layermay use a variety of materials which can be known by those of ordinaryskill in the art without limitation as long as the relationship of therefractive indices represented by General Formula 1 and the thicknessrelationship are satisfied.

In one example, the base layer may include at least one selected fromthe group consisting of a polyester-based resin such aspolyethyleneterephthalate, polycarbonate, polyethylenenaphthalate, orpolyarylate, a polyether-based resin such as polyethersulfone, apolyolefin-based resin such as a cyclo-olefin polymer, a polyethyleneresin, or a polypropylene resin, a cellulose-based resin such asdiacetylcellullose, triacetylcellullose, or acetylcellullosebutylate, apolyimide-based resin, and an epoxy-based resin. In the presentinvention, preferably the base layer may include polycarbonate or acyclo-olefin polymer. In one example, a thickness of the base layer maybe, but is not particularly limited to, 2 to 200 μm, preferably, 5 to190 μm, 10 to 180 μm, 20 to 180 μm, or 20 to 150 μm. In addition, thebase layer may include a separate coated layer laminated on an oppositesurface of the above-described multilayer laminate. The coated layer maybe laminated to a thickness of 0.01 to 10 μm to improve opticalcharacteristics, complement mechanical properties, or give functionalityto make a future process easy.

The material for the inorganic layer is not limited as long as theabove-described range of the refractive index is satisfied, and may beformed of, for example, an oxide or nitride of at least one metalselected from the group consisting of Al, Zr, Ti, Hf, Ta, In, Sn, Zn,and Si. The thickness of the inorganic layer may be 5 to 100 nm, 10 to90 nm, or 10 to 80 nm. In one example, the inorganic layer of thepresent invention may be formed of a zinc oxide-based material. The zincoxide-based material may be a zinc oxide-based material not containingany dopant, or a zinc oxide-based material containing dopants. Thedopant which can be doped to the zinc oxide may be, but not limited to,at least one element selected from the group consisting of Ga, Si, Ge,Al, Sn, Ge, B, In, Tl, Sc, V, Cr, Mn, Fe, Co, and Ni, or an oxidethereof. The dopant may be doped to zinc oxide (ZnO) in the type of acation, which substitutes a Zn moiety and increases the concentration ofelectrons or holes of the zinc oxide-based inorganic layer. However, notto degrade electron mobility, the concentration of the dopant may be 0.1to 20 wt %. Alternatively, when mechanical properties and opticalcharacteristics are adjusted using a dopant, the concentration of thedopant may be increased at 15 to 85 at %. In an exemplary embodiment ofthe present invention, the inorganic layer may be formed of, forexample, zinc tin oxide as long as it satisfies the refractive indexwithout particular limitation. As the zinc tin oxide is applied as theinorganic layer to the barrier film satisfying the above-describedrelation of the refractive indices and the thickness relationship, thebarrier film may exhibit excellent gas barrier properties and opticalcharacteristics.

In an exemplary embodiment of the present invention, the firstdielectric layer or the second dielectric layer may be an organic ororganic-inorganic composite layer. In one example, the first dielectriclayer or the second dielectric layer may include at least one selectedfrom the group consisting of an acrylic resin, a urethane-based resin, amelamine resin, an alkyde resin, an epoxy-based resin, a siloxane-basedpolymer, and an organic silane compound represented by Formula 1.

In Formula 1, X may be hydrogen, a halogen, an alkoxy group, an acyloxygroup, an alkylcarbonyl group, an alkoxycarbonyl group, or —N(R₂)₂, inwhich R₂ is hydrogen or an alkyl group, R₁ is an alkyl group, an alkenylgroup, an alkynyl group, an aryl group, an arylalkyl group, an alkylarylgroup, an arylalkenyl group, an alkenylaryl group, an arylalkynyl group,an alkynylaryl group, a halogen, an amino group, an amide group, analdehyde group, an alkylcarbonyl group, a carboxyl group, a mercaptogroup, a cyano group, a hydroxyl group, an alkoxy group, analkoxycarbonyl group, a sulfonyl group, a phosphoryl group, anacryloyloxy group, a methacryloyloxy group, or an epoxy group, Q is asingle bond, an oxygen atom, or —N(R₂)—, in which R₂ is a hydrogen atomor an alkyl group, and m is a number of 1 to 3.

The organic silane may be at least one selected from the groupconsisting of the compound represented by Formula 1, and when a type oforganic silane compound is used, crosslinking can occur.

An example of the organic silane may be selected from the groupconsisting of methyltrimethoxysilane, methyltriethoxysilane,phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane,dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane,phenyldimethoxysilane, phenyldiethoxysilane, methyldimethoxysilane,methyldiethoxysilane, phenylmethyldimethoxysilane,phenylmethyldiethoxysilane, trimethylmethoxysilane,trimethylethoxysilane, triphenylmethoxysilane, triphenylethoxysilane,phenyldimethylmethoxysilane, phenyldimethylethoxysilane,diphenylmethylmethoxysilane, diphenylmethylethoxysilane,dimethylmethoxysilane, dimethylethoxysilane, diphenylmethoxysilane,diphenylethoxysilane, 3-aminopropyltriethoxysilane,3-glycidoxypropyltrimethoxysilane, p-aminophenylsilane,allyltrimethoxysilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane,3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane,3-glycidoxypropyldiisopropylethoxysilane,(3-glycidoxypropyl)methyldiethoxysilane,3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane,3-mercaptopropyltriethoxysilane,3-methacryloxypropylmethyldiethoxysilane,3-methacryloxypropylmethyldimethoxysilane,3-methacryloxypropyltrimethoxysilane,n-phenylaminopropyltrimethoxysilane, vinylmethyldiethoxysilane,vinyltriethoxysilane, vinyltrimethoxysilane, and a mixture thereof.

In one example, the first dielectric layer or the second dielectriclayer may further include at least one selected from the groupconsisting of pentaerythritol triacrylate, hydroxyethylacrylate,hydroxypropylacrylate, polyethyleneglycol monoacrylate, ethyleneglycolmonoacrylate, hydroxybutylacrylate, glycidoxymethacrylate,propyleneglycol monoacrylate, trimethoxysilylethyl epoxycyclohexane,acrylic acid, and methacrylic acid.

In one example, the epoxy-based resin may be at least one selected fromthe group consisting of an alicyclic epoxy resin and an aromatic epoxyresin.

The alicyclic epoxy resin may be, for example, at least one selectedfrom the group consisting of an alicyclic glycidyl ether-type epoxyresin and an alicyclic glycidyl ester-type epoxy resin. In addition, asan example, Celloxide 2021P (Daicel), that is,3,4-epoxycyclohexyl-methyl-3,4-epoxycyclohexane carboxylate, andderivatives thereof may be used, which may be stable at a hightemperature, colorless and clear, and have excellent toughness, adhesionand adhesive strength for a laminate. Particularly, when the alicyclicepoxy resin is used for coating, excellent surface hardness isexhibited.

The aromatic epoxy resin may be at least one aromatic epoxy resinselected from the group consisting of a bisphenol A-type epoxy resin, abromo bisphenol A-type epoxy resin, a bisphenol F-type epoxy resin, abisphenol AD-type epoxy resin, a fluorene-containing epoxy resin, and atriglycidyl isocyanurate.

An inorganic material for forming the first dielectric layer or thesecond dielectric layer may be a coating composition formed by a sol-gelreaction, for example, at least one selected from the group consistingof SiO_(x) (wherein x is an integer of 1 to 4), SiO_(x)N_(y) (wherein xand y are each an integer of 1 to 3), Al₂O₃, TiO₂, ZrO, and ITO.

In addition, the first dielectric layer or the second dielectric layermay further include at least one selected from the group consisting of ametal alkoxide compound represented by Formula 2.

In Formula 2, M is any one metal selected from the group consisting ofaluminum, zirconium and titanium, R₃ is a halogen, an alkyl group, analkoxy group, an acyloxy group or a hydroxyl group, and z is 3 or 4.

In an exemplary embodiment of the present invention, the firstdielectric layer or the second dielectric layer may further include afiller of nanoparticles to adjust the refractive index. The filler maybe, but is not limited to, a metal oxide or a metal nitride. In oneexample, the filler may include at least one selected from the groupconsisting of CaO, CaF₂, MgO, ZrO₂, TiO₂, SiO₂, In₂O₃, SnO₂, CeO₂, BaO,Ga₂O₃, ZnO, Sb₂O₃, NiO, and Al₂O₃. In addition, when the filler is usedin coating for a dielectric layer, a surface of the filler may betreated as needed to improve an adhesive strength. For example, thesurface of the filler may be treated with epoxy silane, acryl silane, orvinyl silane. The filler may have a diameter of 0.1 to 150 nm, 0.1 to100 nm, 1 to 90 nm, 1 to 70 nm, or 1 to 50 nm. As the size of the filleris controlled in the above range, transparency and a desired refractiveindex of the film of the present invention may be satisfied.

The first dielectric layer or the second dielectric layer may be curedby thermal curing, photocuring, or a combination thereof, and mayfurther include a thermal acid generator or a photo acid generator asneeded.

When the curing is performed with heat, thermal resistance of the baselayer should be considered, and an amorphous base layer may be cured ata glass transition temperature or less, and if having crystallinity, thecuring may be used at a higher temperature than the glass transitiontemperature. For example, a cyclo-olefin copolymer (COP) may be cured at120° C. or less, polycarbonate (PC) may be cured at 130° C. or less,poly(ethylene terephthalate) (PET) may be cured at 130° C. or less, andpolyethylenenaphthalate (PEN) may be cured at 150° C. or less.

The present invention also relates to a method of manufacturing theabove-described barrier film. The exemplary manufacturing method mayinclude sequentially laminating a first dielectric layer, an inorganiclayer having a refractive index of 1.65 or more, and a second dielectriclayer on a base layer. In addition, the first dielectric layer, theinorganic layer, and the second dielectric layer may satisfy GeneralFormula 1, the thickness of the first dielectric layer may be less than100 nm, the thickness of the second dielectric layer may be equal to orlarger than the thickness of the first dielectric layer.

n ₂ ≦n ₁ <n _(i)  [General Formula 1]

In General Formula 1, n₁ is a refractive index of the first dielectriclayer, n₂ is a refractive index of the second dielectric layer, andn_(i) is a refractive index of the inorganic layer.

To sequentially form the first dielectric layer, the inorganic layer,and the second dielectric layer on the base layer, vacuum evaporation,sputtering, atomic layer deposition, ion plating, or coating may beused, but the present invention is not limited thereto, and thus acommon method known to the art may be used.

EFFECT

A barrier film of the present invention can be applied to an organic orinorganic phosphor device, a display device, or a photovoltaic device toeffectively block chemical materials such as water or oxygen, protect anelectronic device therein, and maintain excellent opticalcharacteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an exemplary barrier film according to thepresent invention.

DESCRIPTIONS OF REFERENCE NUMERALS

-   -   10: barrier film    -   11: second dielectric layer    -   12: inorganic layer    -   13: first dielectric layer    -   14: base layer

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the present invention will be described in further detailwith reference to examples according to the present invention andcomparative examples not according to the present invention. However,the scope of the present invention is not limited to the followingexamples.

Example 1

A first dielectric layer having a refractive index of 1.65 was formed tohave a thickness of 40 nm on a polycarbonate (PC) film (thickness: 100μm, refractive index: 1.61) using a coating solution (TYT65, Toyo InkCo., Ltd.) prepared by including metal oxide nanoparticles (titaniumdioxide) in an acryl resin. Specifically, the coated layer was formed bycoating the PC film with the coating solution using a meyer bar, dryingthe coated film at 100° C. for approximately 2 minutes, and irradiatingthe dried film with UV rays for coating at an intensity of 0.5 J/cm².Zinc tin oxide having a refractive index of 2.0 was deposited on thefilm coated as described above as an inorganic layer to a thickness ofapproximately 20 nm by sputtering in a 3 mTorr argon atmosphere. Asecond dielectric layer having a refractive index of 1.48 was formed onthe deposited layer to a thickness of 91 nm using a coating solutionprepared of pentaerythritol triacrylate and methylethoxy silane in aweight ratio of 40:60, and thus a barrier film was manufactured.Specifically, a half of the total weight of the pentaerythritoltriacrylate used in the coating solution was a reaction product withisocyanato triethoxysilane. The coating solution was prepared byhydrating a mixture of the pentaerythritol triacrylate and methoxysilaneusing 2 equivalent of water based on silanol and 1.5 parts by weight of0.1 N hydrochloric acid based on the solid content at room temperaturefor 30 hours. The second dielectric layer was formed by coating the PCfilm with the coating solution using a meyer bar, drying the coated filmat room temperature for 3 minutes, and drying the resulting product at100° C. for 1 minute.

Comparative Example 1

A barrier film was manufactured by the same method as described inExample 1, except that a first dielectric layer was formed to have athickness of 91 nm, and a second dielectric layer was formed to have athickness of 40 nm.

Comparative Example 2

A barrier film was manufactured by the same method as described inExample 1, except that a dielectric layer (thickness: 40 nm) having arefractive index of 1.48 was formed as a first dielectric layer using acoating solution prepared of pentaerythritol triacrylate andmethylethoxy silane in a weight ratio of 40:60, and a dielectric layer(thickness: 91 nm) having a refractive index of 1.65 was formed as asecond dielectric layer using a coating solution (TYT65, Toyo Ink Co.,Ltd.) including metal oxide nanoparticles in an acryl resin.

Example 2

A barrier film was manufactured by the same method as described inExample 1, except that a first dielectric layer was formed to have athickness of 20 nm and a second dielectric layer was formed to have athickness of 100 nm.

Comparative Example 3

A barrier film was manufactured by the same method as described inExample 2, except that a second dielectric layer was not used.

Example 3

A barrier film was manufactured by the same method as described inExample 1, except that a PET film (thickness: 50 μm, refractive index:1.64) was used as a base layer, a first dielectric layer was formed tohave a thickness of 40 nm, and a second dielectric layer was formed tohave a thickness of 100 nm.

Example 4

A barrier film was manufactured by the same method as described inExample 1, except that a cyclo-olefin copolymer (COP) film (thickness:50 μm, refractive index: 1.53) was used as a base layer, a firstdielectric layer was formed to have a thickness of 35 nm, and a seconddielectric layer was formed to have a thickness of 960 nm.

Comparative Example 4

A first dielectric layer having a refractive index of 1.48 was formed ona PC film (thickness: 100 μm, refractive index: 1.61) to a thickness of0.1 μm using a coating solution prepared of pentaerythritol triacrylateand methylethoxy silane in a weight ratio of 40:60. A zinc tin oxidelayer having a refractive index of 2.0 was deposited on the coated filmas an inorganic layer to a thickness of approximately 20 nm bysputtering in a 3 mTorr argon atmosphere. A second dielectric layer wasformed on the deposited layer to a thickness of 0.26 μm using thecoating solution, and thus a barrier film was manufactured.

Example 5

A barrier layer was formed by the same method as described in Example 4,except that a first dielectric layer was formed to have a thickness of75 nm, and a second dielectric layer was formed to have a thickness of75 nm.

1. Measurement of Refractive Index and Thickness

Refractive indices and thicknesses of the first dielectric layers, thesecond dielectric layers, and the inorganic layers according to Examplesand Comparative Examples of the present invention were measured by thefollowing methods.

Samples for measuring a refractive index were prepared by forming adielectric layer or an inorganic layer on a Si substrate. The refractiveindex of the sample was obtained by analysis using an ellipsometer(M2000U, J.A. Woolam Co.).

The thicknesses of layers coated on a base layer were measured using ascanning electron microscope (S4800, Hitachi).

2. Measurement of Average Light Transmittance

Optical transmission spectrums of the barrier films manufacturedaccording to Examples and Comparative Examples were evaluated usingShimadzu UV3600 (average light transmittance from 380 to 780 nm).

3. Measurement of Water Vapor Transmission Rate (WVTR)

WVTRs of the barrier films manufactured according to Examples andComparative Examples were evaluated using Lyssy L80 at 30° C. and 100%R.H.

4. Measurement of Yellowness Index and CIE Value

Yellowness index (according to ASTM E313) and a* and b* values in theCIE color coordinates of the barrier films manufactured according toExamples and Comparative Examples were obtained from a lighttransmission spectrum using a utility provided by Shimadzu.

TABLE 1 Average light Yellow- WVTR transmittance ness (g/m² (%) a* b*index day) Example 1 90.7 −0.7 0.2 0.0 <0.03 Example 2 90.8 −1.0 1.3 1.8<0.03 Example 3 91.7 −0.9 1.2 1.6 <0.03 Example 4 91.1 −0.7 −0.4 −1.3<0.03 Example 5 90.2 −0.7 −0.4 −1.3 <0.03 Comparative 85.7 −0.1 1.3 2.5<0.03 Example 1 Comparative 87.5 −0.2 −1.2 −2.5 <0.03 Example 2Comparative 84.5 −0.1 2.9 5.6 <0.03 Example 3 Comparative 86.6 −0.6 −2.5−5.5 <0.03 Example 4

What is claimed is:
 1. A barrier film satisfying General Formula 1,sequentially comprising: a base layer, a first dielectric layer, aninorganic layer having a refractive index of 1.65 or more, and a seconddielectric layer, wherein the first dielectric layer has a thickness ofless than 100 nm, a thickness of the second dielectric layer is equal toor larger than that of the first dielectric layer:n ₂ ≦n ₁ ≦n _(i)  [General Formula 1] wherein n₁ represents a refractiveindex of the first dielectric layer, n₂ represents a refractive index ofthe second dielectric layer, and n_(i) represents the refractive indexof the inorganic layer.
 2. The barrier film according to claim 1, whichsatisfies General Formula 4:0.01≦d ₁ /d ₂≦1  [General Formula 4] wherein d₁ represents the thicknessof the first dielectric layer, and d₂ represents the thickness of thesecond dielectric layer.
 3. The barrier film according to claim 1,wherein the thickness of the second dielectric layer d₂ is 10 nm to 1μm.
 4. The barrier film according to claim 1, wherein the refractiveindex of the first dielectric layer n₁ and the refractive index of thesecond dielectric layer n₂ satisfy General Formula 2:0.5≦(n ₂−1)/(n ₁−1)≦1.  [General Formula 2]
 5. The barrier filmaccording to claim 1, wherein the refractive index of the firstdielectric layer n₁ and the refractive index of the inorganic layern_(i) satisfy General Formula 3:0.3≦(n ₁−1)/(n _(i)−1)≦0.95.  [General Formula 3]
 6. The barrier filmaccording to claim 1, wherein a refractive index of the base layer is1.45 to 1.75.
 7. The barrier film according to claim 1, wherein therefractive index of the base layer n_(s) and the refractive index of theinorganic layer n_(i) satisfy General Formula 5:n _(s) <n _(i).  [General Formula 5]
 8. The barrier film according toclaim 1, wherein a refractive index of the base layer n_(s) and arefractive index of the first dielectric layer n_(i) satisfy GeneralFormula 6:0.5≦n _(s) /n ₁≦1.5.  [General Formula 6]
 9. The barrier film accordingto claim 1, wherein a refractive index of the first dielectric layer n₁or a refractive index of the second dielectric layer n₂ is 1.35 to 1.9.10. The barrier film according to claim 1, wherein yellowness indexaccording to ASTM E313 is −2.0 to 2.0.
 11. The barrier film according toclaim 1, wherein the inorganic layer comprises an oxide or nitride of atleast one metal selected from the group consisting of Al, Zr, Ti, Hf,Ta, In, Sn, Zn and Si.
 12. The barrier film according to claim 1,wherein the inorganic layer is formed of zinc tin oxide.
 13. The barrierfilm according to claim 1, wherein the first dielectric layer or thesecond dielectric layer is an organic or organic-inorganic compositelayer.
 14. The barrier film according to claim 13, wherein the firstdielectric layer or the second dielectric layer comprises at least oneselected from the group consisting of an acrylic resin, a urethane-basedresin, a melamine resin, an alkyde resin, an epoxy-based resin, asiloxane-based polymer, and an organic silane compound represented byFormula 1:

wherein X is hydrogen, a halogen, an alkoxy group, an acyloxy group, analkylcarbonyl group, an alkoxycarbonyl group or —N(R₂)₂, in which R₂ ishydrogen or an alkyl group, R₁ is an alkyl group, an alkenyl group, analkynyl group, an aryl group, an arylalkyl group, an alkylaryl group, anarylalkenyl group, an alkenylaryl group, an arylalkynyl group, analkynylaryl group, a halogen, an amino group, an amide group, analdehyde group, an alkylcarbonyl group, a carboxyl group, a mercaptogroup, a cyano group, a hydroxyl group, an alkoxy group, analkoxycarbonyl group, a sulfonyl group, a phosphoryl group, anacryloyloxy group, a methacryloyloxy group or an epoxy group, Q is asingle bond, an oxygen atom or —N(R₂)—, in which R₂ is a hydrogen atomor an alkyl group, and m is a number of 1 to
 3. 15. The barrier filmaccording to claim 13, wherein the first dielectric layer or the seconddielectric layer comprises at least one selected from the groupconsisting of metal alkoxide compounds represented by Formula 2:

wherein M is one metal selected from the group consisting of aluminum,zirconium and titanium, R₃ is a halogen, an alkyl group, an alkoxygroup, an acyloxy group or a hydroxyl group, and z is 3 or
 4. 16. Thebarrier film according to claim 13, wherein the first dielectric layeror the second dielectric layer further comprises fillers.
 17. A methodfor preparing the barrier film according to claim 1, comprising:sequentially laminating a first dielectric layer, an inorganic layerhaving a refractive index of 1.65 or more, and a second dielectriclayer, which satisfy General Formula 1, on a base layer:n ₂ ≦n ₁ <n _(i)  [General Formula 1] wherein n₁ represents a refractiveindex of the first dielectric layer, n₂ represents a refractive index ofthe second dielectric layer, and n_(i) represents the refractive indexof the inorganic layer.